1
Q
What are embedded systems?
A
- A small computer that forms part of a larger system, device or machine
- They tend to have one or limited number of task that can be performed
2
Q
What is the Von Neumann architecture?
A
it’s where both the data and the software that are currently being used are stored in
computer memory (RAM).
3
Q
What is the purpose of a CPU?
A
- To proccess Data
- Where all sorting, searching, calculating and decision making takes place
4
Q
How does the CPU relate to the fetch decode execute cycle?
A
The CPU:
- Fetches instructions from the memory (RAM)
- It Decodes those instructions
- It then Executes (carries out) the instructions
5
Q
What are the main components of the CPU?
A
- Control Unit (CU)
- Arithmetic Logic Unit (ALU)
- Registers
- The CPU also contains data buses
6
Q
What does the Control Unit (CU) do?
A
- controls the way data moves around the CPU
- controls/monitors the flow of data between the CPU and other hardware components
- executes the instructions provided by the program
7
Q
What does the Arithmetic Logic Unit (ALU) do?
A
- performs standard arithmetic operations such as addition, subtraction etc
- deals with logic and comparisons such as “is this value greater than that value?:
8
Q
What do the Registers do?
A
Its a type of temporary memory located inside the CPU. Registers are super fast and are used instead of RAM.
9
Q
What do Buses do?
A
Their role is to carry data around the system.
10
Q
What is the Address Bus?
A
Carries the addresses of data (but not the data) between the processor and memory
11
Q
What is a Data Bus?
A
Carries data between the processor, the memory unit and the input/output devices
12
Q
What is a Control Bus?
A
Carries control signals/commands from the CPU (and status signals from other devices). Therefore coordinating all the activites within the computer.
13
Q
What is a program counter (PC) ?
A
- Hold value of address of next intruction to run
14
Q
What is Memory Address Register (MAR)?
A
- Holds location in memory (address) of next piece of data or program to be fetched
15
Q
What is Memory Data Register (MDR)?
A
- When the program instruction is fetched from memory, it is temporarily held in this register
16
Q
What is Current Data Register (CDR)?
A
- holds the current instruction to be executed, having been fetched from memory.
17
Q
What is the full steps of the Fetch, Decode, Execute Cycle?
A
- PC had address of next Instruction
- PC copied to MAR
- Lookup MAR and get contents and copy into MDR
- Copy MDR into CIR
- PC incremented by 1
- Instruction decoded and executed
- Repeat.
18
Q
What is Clock Speed?
A
The Clock is a vibrating crystal inside the CPU. The faster it vibrates that faster
instructions are processed.
19
Q
What is Hertz?
A
number of cycles/operations per second
20
Q
What are Cores?
A
A processor has a “core” in which instructions are executed. There
can be multiple cores: Dual Core, Quad Core.
Each core executes instructions independently.
21
Q
What is Multitasking?
A
working on different tasks at the same time
22
Q
What is Parralel Processing?
A
all cores work together on the same task.
23
Q
What is Cache?
A
Very fast, and usually a very small amount of memory on the processor chip.
- As programs are executing – the Cache holds commonly used instructions
24
Q
What affects the performance of a Computer?
A
ClockSpeed, Cores and Cache Size
25
What is Memory (Primary Memory)?
- Area where Computer stores or remembers data which provide CPU with Instructions
26
What is Volatile Memory?
- Only stores data when the computer is on.
- When the computer is turned off its reset and emptied.
- Requires Power to store data.
27
What is Non-Volatile Memory?
- Stores data when the computer is off
- Do not require power
28
What is RAM (Random Access Memory) ?
Used to store data that the computer is currently working on
29
What is ROM (Read only Memory)?
- flash memory chip that contains a small amount of memory.
- It retains its memory after the computer is turned off.
30
What is BIOS?
- ROM contains the BIOS which is the firmware for the motherbaord that boots the computer.
- The BIOS contains the bootstrap - program leading up to the loading of the operating system
31
What are the differences between RAM and ROM
**RAM:**
- Volatile memory
- Faster than secondary storage (hard disk)
- Can be read and written
**ROM:**
- Non - Volatile Memory
- Contents cannot be change
- Can only be read
32
What is Virtual Memory?
- When the RAM is full, the computer creates a virtual area on the hard disk to imiate RAM
- Once the user starts shutting down the running programs, It will free up the RAM and the virtual area will be deleted.
33
What is Disk Thrashing
Its a condition where the system spends excessive time swapping pages between memory and disk, resulting in poor performance.
34
What is Secondary Storage?
storing data and program files when the power supply is turned off. Therfore Must be
non-volatile.
35
Differences Between **Secondary Storage** vs **Memory (Primary Storage)** ?
**Secondary Storage:**
- Read/Write speeds are much slower to access
- Data is Permanent
- Higher Storage Capacity
**Memory (Primary Storage):**
- Read/Write speeds are faster to access
- Data is lost when computer turned off.
- Lower Storage Capacity
36
What is Magnetic Storage, And how does it work?
Magnetic disks consist of stacks of non-removable disks coated with magnetic material.
- Data is stored magnetically on the surface of these disks, either its magnetised(1) or demagnetised(0). 10010110
- An electromagnet in the read/write head charges the disk’s surface with either a positive or negative charge, this is how binary 1 or 0 is represented.
37
What is Solid State Drive (SSD), And how does it work?
Solid state drives are non-volatile storage devices capable of holding large amounts of data.
-use NAND flash memories (millions of transistors wired in a series on a circuit board)
- giving them the advantage of having no mechanical moving parts and therefore immediate access to the data.
38
Positives and Negatives of Solid State Drive?
**Positives:**
- Extremely fast read/write speeds
- Small in physical size and very light
- No moving parts to wear, fail or get damaged
**Negatvies:**
- Expensive to buy (per GB)
- Limited in capacity due to the expense
- Limited amount of writes
39
What is Optical Storage, And how does it work?
Compact Disc (CDs) that store 700MB
Digital Versatile Disks (DVDs) that store 4.7GB
Blu-ray discs that can store up to 50GB
1. Data is written by a laser burning the surface
2. Binary data is stored as variations of height on the surface in the forms of patterns of dots.
3. When light from laser is shined on a disk where there is a pit it is reflected differently to a flat area. Allowing the drive to detect differences and read the data.
40
What is Cloud computing?
storing and accessing data or programs through the
Internet.
service where files can be uploaded via the Internet to a remote server (usually stored on HDDs and SSDs).
41
What is Software-as-a-service (SaaS)?
software that is delivered through the Internet, and usually accessed by a web
browser.
- e.g. Google Apps, MailChimp, Office Online, Dropbox
42
What is infastructure-as-a-service (IaaS)?
Hardware Resources are available online.
This is usually related with hardware. Such as networking and servers. It allows
businesses to purchase resources on demand (when they only need them).
- e.g. Amazon Web Services (AWS), Microsoft Azure, DigitalOcean
43
What are the Pros, and Cons of Cloud Storage?
Pros:
- Users can access files from any connected device
- Files can be shared with others or made public
- No need to buy expensive hardware to store data
Cons:
- Need connection to the Internet to access file
- Stored data can be vulnerable to hackers
- Subscription fees for using cloud storage may be expensive in the long run
44
What do IP addresses do?
They Identify a connection of a computer on the internet which are assigned by an Internet service provider or network administrator
45
What are the differences between IPv4 and IPv6
IPv4 :
- 32 bit
- 8 bits per octet
- 4 billion unique addresess
IPv6:
- 128 but address
- 8 bits per number
- 340 trillion trillion trillion addresses
- uses hexadecimal
46
What are routers? And what do they do?
- allow packets from different network types to be exchanged.
- They send data packets to specific destinations on the network
-
47
What is a Switch?
An interconnection device that connects two or more devices together in the same network.
48
What is Wireless Acess Point (WAP)?
- Allows wireless devices to connect to a network (either LAN or WAN)
- WAPs provide Internet access in public places (often known as Wi-Fi hotspots)
49
What is Network Interface Card (NIC)?
- allows a computer to connect to a wired network.
- contains a MAC address which is a physical hardware address
- allows an Ethernet cable to be plugged into this
50
What is MAC Address?
- unique code which is built into the Network Interface Card (NIC)
- embedded into the device when it is manufactured and the owner cannot change it.
- made up of 48 bits, usually written in hexadecimal for ease.
51
What are input Devices?
Data or control signals sent to computer
52
What are Outpud Devices?
pieces of computer hardware used to communicate the results of data processing
53
What are Sensors?
input devices that record data about the physical environment around it.
54
How does sound go from Sound waves to Electric Current?
1. Anologue Signal to Digital Signal = Anologue to digital converter (ADC)
2. Digital Signal to Electical Current = Digital to Analogue converter (DAC)
IGCSE Computer Science (CIE)
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